Steam methane reforming unit for carbon capture

ABSTRACT

A molten carbonate fuel cell-powered system for capturing carbon dioxide produced by a steam methane reformer system. Tail gas from a pressure swing adsorption system is mixed with exhaust gas from the fuel cell anode, then pressurized and cooled to extract liquefied carbon dioxide. The residual low-CO2 gas is directed to an anode gas oxidizer, to the anode, to the reformer to be burned for fuel, and/or to the pressure swing adsorption system. Low-CO2 flue gas from the reformer can be vented to the atmosphere or directed to the anode gas oxidizer. Reduction in the amount of CO2 reaching the fuel cell allows the fuel cell to be sized according to the power demands of the system and eliminates the need to export additional power output.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application claims the benefit of and priority to U.S. ProvisionalApplication No. 62/987,985, filed Mar. 11, 2020, the entire disclosureof which is hereby incorporated by reference herein.

BACKGROUND

The present disclosure relates to a Steam Methane Reformer (SMR). Inparticular, the present disclosure relates to a SMR with enhanced carbondioxide (CO₂) capture.

Steam methane reformers (SMRs) are generally used to produce a syngasfrom a gas feedstock such as natural gas or refinery gas. The producedsyngas can be further processed within the plant to yield various endproducts, including purified hydrogen, methanol, carbon monoxide, andammonia. However, the flue gas produced during the reforming processcontains contaminants, such as carbon dioxide, which are known toadversely affect the environment by contributing to overall climatechange. SMR's are known to be one of the largest CO₂ emitters inrefineries. As such, in recent years, many government regulatory bodieshave required the reduction in emissions of carbon dioxide, into theatmosphere.

Given the recognition of the harmful effect of carbon dioxide releaseand recent restrictions on its emission, efforts have been made toefficiently remove carbon dioxide in a purified form from a flue gasproduced by a steam reformer plant. By removing carbon dioxide from theflue gas, the carbon dioxide alternatively may be used for other, saferpurposes, such as underground storage or oil production needs.

Current methods for CO₂ capture from SMRs, such as for example, using anamine absorption stripper system to remove CO₂ from flue gas (postcombustion capture) or using physical or amine-based chemical solventsin a stripper system to remove CO₂ from the SMR tail gas (pre-combustioncapture), are highly inefficient and costly. The stripping systems aregenerally too energy intensive, requiring significant quantities ofsteam to regenerate the solvents. The state-of the-art post-combustionmethod employing molten carbonate fuel cell (MCFC) technology generatespower while capturing CO₂ from a host plant. The additional powergenerated beyond the requirements of the system itself provides a sourceof revenue which offsets system capital and operating costs. In theconventional post-combustion system, flue gas from the SMR containinghigh levels of CO₂ are directed into the MCFC. Due to the high levels ofCO₂, this method requires a relatively large quantity of MCFC modules,which can be costly, and may produce more power than is desirable. Assuch, conventional MCFC-based CO₂ capture systems can be very expensiveand may produce excess energy than cannot easily be unloaded.

SUMMARY

Embodiments described herein provide a SMR-CO₂ capture system thatcaptures CO₂ from a tail gas of a pressure swing adsorption (PSA) systemof a SMR system, which can, advantageously, help to capture CO₂ in amore efficient and cost effective manner, as compared to someconventional CO₂ capture systems.

In some embodiments, a system for capturing CO₂ from a SMR systemcomprises a MCFC, a compressor, a chiller, and a CO₂ separator. Exhaustgas from the anode of the MCFC may be mixed with tail gas from a PSA ofthe SMR system and compressed by the compressor. The mixed, compressedgas may be cooled by the chiller and fed into the CO₂ separator. The CO₂separator separates liquefied CO₂ from the residual, uncondensed gas.

In various embodiments, the residual gas may be recycled into variousparts of the SMR system or the system for capturing CO₂. For example, insome embodiments, a portion of the gas may be recycled to an anode gasoxidizer and then to a cathode of the MCFC, and another portion recycledinto an anode of the MCFC. In some embodiments, a third portion of theresidual gas may be recycled to the PSA of the SMR system to producemore hydrogen, or to a reformer in the SMR system to be burned as fuel.This third portion of residual gas may instead be recycled for use in aPSA outside the SMR system. In some embodiments, a third portion of theresidual gas may be recycled to the PSA of the SMR system to producemore hydrogen, and a fourth portion of the residual gas may be recycledto a reformer in the SMR system to be burned as fuel.

In some embodiments, flue gas from a reformer of the SMR system may bevented to the atmosphere. Because the tail gas from the PSA of the SMRsystem is not burned to fuel the reformer of the SMR system, the fluegas is relatively low in CO₂. In other embodiments, the flue gas may bedirected to an anode gas oxidizer in the system for capturing CO₂ andthen to a cathode of the MCFC.

In some embodiments, the MCFC may be sized to power only the system forcapturing CO₂, only the SMR system, or both. Because the tail gas fromthe PSA of the SMR system is not burned to fuel the reformer of the SMRsystem, the MCFC receives a reduced amount of CO₂, allowing the MCFC tobe sized smaller and reducing excess power generation.

In some embodiments a system for capturing CO₂ from a SMR systemcomprises a compressor, a chiller, and a CO₂ separator, but excludes anMCFC as power for the system may be derived from an external powersource such as an existing power plant, utility grid, and/or renewablepower such as solar or wind power. Tail gas from a PSA of the SMR systemis compressed by the compressor and cooled by the chiller. The CO₂separator separates liquefied CO₂ from the residual, uncondensed gas.The uncondensed gas may then be recycled to the PSA of the SMR systemand/or to the reformer of the SMR system to be burned as fuel.

In some embodiments, a method comprises mixing anode exhaust gas fromthe anode of a MCFC a with tail gas from the PSA of a SMR system,compressing the mixed gas with a compressor, cooling the mixed gas witha chiller, separating liquefied CO₂ from residual, uncompressed gas in aseparator, and collecting the liquefied CO₂. In some embodiments, theresidual gas may be recycled in varying amounts to an anode gas oxidizercoupled to a cathode of the MCFC, the anode of the MCFC, the PSA of theSMR system, and/or to a reformer of the SMR system to be burned as fuel.

The foregoing is a summary of the disclosure and thus by necessitycontains simplifications, generalizations, and omissions of detail.Consequently, those skilled in the art will appreciate that the summaryis illustrative only and is not intended to be in any way limiting.Other aspects, features, and advantages of the devices and/or processesdescribed herein, as defined by the claims, will become apparent in thedetailed description set forth herein and taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

The disclosure will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingfigures, wherein like reference numerals refer to like elements, inwhich:

FIG. 1 shows a schematic view of a conventional SMR-CO₂ capture system.

FIG. 2 shows a schematic view of a SMR-CO₂ capture system, in accordancewith a representative embodiment of the present disclosure.

FIG. 3 shows a schematic view of a SMR-CO₂ capture system, in accordancewith another representative embodiment.

FIG. 4 shows a schematic view of a SMR-CO₂ capture system, in accordancewith yet another representative embodiment.

FIG. 5 shows a schematic view of a SMR-CO₂ capture system, in accordancewith yet another representative embodiment.

FIG. 6 shows a method of capturing CO₂ from a SMR, in accordance with arepresentative embodiment.

DETAILED DESCRIPTION

Referring generally to the figures, disclosed herein are variousembodiments of an enhanced SMR-CO₂ capture system capable of capturingCO₂ in a more efficient and cost effective manner, as compared to someconventional CO₂ capture systems. The various embodiments disclosedherein may be capable of increasing the amount of CO₂ captured,improving efficiency of capturing CO₂, increasing the amount of hydrogenproduced, and/or reducing costs associated with capturing CO₂. In thevarious embodiments disclosed herein, like reference numerals refer tolike elements between Figures, but are increased by 200 from figure tofigure (e.g., PSA 450 in FIG. 2 is the same as PSA 650 in FIG. 3, etc.).

Generally speaking, in a typical SMR unit of a SMR-CO₂ capture system,natural gas is reacted with water to form hydrogen and CO₂. Some methaneis unconverted and some carbon monoxide is also generated in theprocess. These impurities, along with any water that is not separatedout by condensation, is normally removed from the hydrogen using a PSAsystem, which can desorb these impurities at atmospheric pressure togenerate a PSA tail gas that is generally high in CO₂ and also containsCO, methane, and hydrogen. Typically, the PSA tail gas is recycled asfuel in the SMR unit, where the gases are combusted with air to providethe heat needed for the endothermic reforming reaction. This reactionproduces a flue gas having relatively high CO₂ content that can bedirected to an MCFC for subsequent CO₂ capture. In this type of systemconfiguration, the size of the MCFC is dictated, in part, by the amount(or percentage) of CO₂ to be transferred to the anode of the MCFC fromthe flue gas received from the SMR unit (e.g., 70%-90% of the CO₂).

However, the composition of the PSA tail gas is very similar to theshifted anode exhaust gas of the MCFC in the CO₂ capture system. Thus,Applicant advantageously determined that the PSA tail gas could be mixeddirectly with the anode exhaust gas of the MCFC before being compressedand cooled to separate the CO₂ from the gas, instead of recycling thePSA tail gas in the SMR unit. In this manner, the size of the MCFC isnot dictated by the PSA tail gas from the SMR unit, since the CO₂ thatis normally contained in the flue gas from the PSA tail gas is mixedwith the anode exhaust gas downstream of the MCFC for subsequent CO₂capture instead. Accordingly, the overall cost of the system can bereduced by selecting a smaller sized MCFC that can, for example, producejust enough power for the chiller and other electrical loads of the CO₂capture system, the SMR system itself, or both, as discussed in greaterdetail below.

In some implementations, the system can also be configured to direct theflue gas from the SMR unit to the MCFC for additional CO₂ capture. Insome implementations, the unused fuel from the anode of the MCFCcontaining hydrogen and carbon monoxide can be directed from a CO₂capture tail gas to the PSA to increase the hydrogen production of thesystem. In some implementations, power is purchased from an externalsource instead of using an MCFC to power the CO₂ capture system.

FIG. 1 shows a typical SMR-CO₂ capture system. As shown in FIG. 1, steamsupplied by a steam supply line 210 and natural gas supplied by anatural gas supply line 220 are mixed and fed to a reformer 230 of areformer system 200 for converting the methane to hydrogen, CO₂, and CO.The reformer effluent may be transported to a shifting assembly of thereformer system 200, where the effluent may be cooled and most of the COcan be shifted to hydrogen according to the reaction:

CO+H₂O↔H₂+CO₂

The shifted gas is then sent via shift gas line 240 to a PSA system 250where the hydrogen is separated from the residual methane and CO in thegas along with the CO₂ produced from the reforming and shift reactions.The residual gases are recycled as fuel to the reformer 230 via arecycling line 260, where the gases are combusted with air supplied byan air supply line 270 to provide the heat needed for the endothermicreforming reaction. All of the CO₂ generated in the production of thehydrogen is vented in the reformer flue gas as a mixture of N₂, CO₂, andH₂O with some NOx.

Still referring to FIG. 1, the reformer flue gas containing the CO₂ issent to an AGO (anode gas oxidizer) 110 of a CO₂ capture system 100where the flue gas is optionally combined with air, if required toincrease the flue gas oxygen content to the level required for MCFCoperation, from an air supply line 112. The flue gas and air are heatedand fed into a cathode 124 of an MCFC 120. Natural gas is provided to apre-heater 115 before being fed to an anode 122 of the MCFC 120 via anatural gas supply line 114. Due to the unique properties of the MCFC,CO₃ ⁼ is transferred from the cathode 124 to the anode 122 of the MCFC120 during normal power production of the MCFC. This transfer removesCO₂ and O₂ from the flue gas containing cathode feed and generates acathode exhaust, which is relatively low in CO₂, thereby reducing CO₂emissions. The CO₃ ⁼ transferred to the anode 122 reacts with hydrogenin the anode 122 to form H₂O and CO₂ while generating power. In thecarbon capture process, the outlet stream from the anode 122 is cooledby, for example, an evaporator 125, and enters a shift reactor such thatCO in the outlet stream is converted to hydrogen and CO₂ using thefollowing shift reaction:

CO+H₂O↔H₂+CO₂

The outlet stream is then compressed by a compressor 130 and then cooledby, for example, a chiller 135. The compressed and cooled outlet streamis then transferred to a CO₂ separator 140. In the compressed and cooledoutlet stream, about 60% to about 90% of the CO₂ is condensed as aliquid and separated from a residual CO₂ capture tail gas containinghydrogen, any unconverted CO, the remaining uncondensed CO₂, andmethane. The residual CO₂ capture tail gas is partially recycled to theanode 122 via a recycle line 142 to be used as fuel in the MCFC 120. Theremainder of the residual CO₂ capture tail gas is sent to the AGO 110 tohelp to prevent buildup of inert gases, such as nitrogen, and to heat upthe gas in the AGO 110 by combusting the remaining hydrogen gas from theresidual CO₂ capture tail gas. This recycling has the advantage ofincreasing the amount of CO₂ recovered from the anode exhaust.

In the system of FIG. 1, the MCFC 120 is sized, in part, based on theamount of CO₂ in the flue gas to transfer to the anode 122 (e.g., about70% to about 90% of the CO₂ in the flue gas). Thus, the systemconfiguration of FIG. 1 can be costly to implement and may generate morepower than desirable.

Referring now to FIG. 2, a SMR-CO₂ capture system including a CO₂capture system 300 and a SMR system 400 is shown according to anexemplary embodiment of the present disclosure. In contrast to thesystem of FIG. 1, the flue gas from the SMR system 400 is not directedto the MCFC for CO₂ capture, but is instead vented since it hasgenerally low CO₂ content. Instead, the SMR system 400 is configuredsuch that a PSA tail gas from a PSA 450 in the SMR system 400 is mixeddirectly with an anode exhaust gas from an anode 322 of an MCFC 320,where the mixture can be compressed and cooled, such that liquefied CO₂can be separated from the mixture to be captured. In this way, the sizeof the MCFC 320 is independent of the flue gas from the SMR reformer430, such that the MCFC 320 may be sized to provide only the powerneeded by the CO₂ capture system 300, the SMR system 400, or both,thereby reducing the overall cost of the system while still providingadequate CO₂ capture.

Still referring to FIG. 2, steam supplied by a steam supply line 410 andnatural gas supplied by a natural gas supply line 420 are mixed and fedto a SMR reformer 430 of a SMR system 400 for converting the methane tohydrogen, CO₂, and CO. The reformer effluent may be transported to ashifting assembly of the SMR system 400, where the effluent may becooled and most of the CO can be shifted to hydrogen. The shifted gas isthen sent via shift gas line 440 to a PSA 450 where the hydrogen isseparated from the residual methane and CO in the gas along with the CO₂produced from the reforming and shift reactions. Instead of recyclingthe residual gases in the PSA tail gas as fuel in the SMR reformer 430,as in the system of FIG. 1, the PSA tail gas is directed to the CO₂capture system 300 by a PSA tail gas supply line 460 to be mixeddirectly with the anode exhaust gas of the anode 322 of the MCFC 320 forsubsequent CO₂ capture. In this way, the size of the MCFC 320 is notdictated by the amount of CO₂ in the PSA tail gas to be transferred tothe anode 322. The MCFC 320 can therefore be sized to anyspecifications, for example, to produce sufficient power for the CO₂capture system 300, the SMR system 400, or both.

Still referring to FIG. 2, the mixture of anode exhaust gas and the PSAtail gas is then compressed by a compressor 330 and then cooled by, forexample, a chiller 335. The compressed and cooled outlet stream is thentransferred to a CO₂ separator 340. In the compressed and cooled outletstream, about 60% to about 90% of the CO₂ is condensed as a liquid andseparated from a residual CO₂ capture tail gas containing hydrogen, anyunconverted CO, the remaining uncondensed CO₂, and methane. A portion ofthe CO₂ capture tail gas stream is recycled to the anode 322 via arecycle line 342 to be used as fuel in the MCFC 320, with a smallportion of the tail gas also being sent to the AGO 310 to help toprevent buildup of inert gases, such as nitrogen, and to heat up the gasin the AGO 310 by combusting the remaining hydrogen gas from theresidual CO₂ capture tail gas.

In the system configuration of FIG. 2, the PSA tail gas is no longerbeing directed back to the SMR Reformer 430 for subsequent burning. Assuch, natural gas may be used instead to provide fuel to SMR Reformer430, and the resulting flue gas containing a relatively low amount ofCO₂ can be vented as a mixture of N₂, CO₂, and H₂O with some NOx asallowed by regulation. In this configuration, about 50% to about 60% ofthe CO₂ normally emitted from the SMR is captured.

According to another representative embodiment shown in FIG. 2, aportion of the residual CO₂ capture tail gas may also be directed backto SMR Reformer 430 by a CO₂ capture tail gas supply line 344(represented by dashed lines/arrows). The portion of the residual CO₂capture tail gas can be used as fuel in SMR Reformer 430, so as toreduce the amount of natural gas required. The portion of the residualCO₂ capture tail gas may also be recycled to the PSA 450, as shown inFIG. 2, to increase the H₂ production of the PSA without increasing thesize of SMR Reformer 430. According to another representativeembodiment, the MCFC 320 may be sized to use only the residual CO₂capture tail gas as fuel, thereby eliminating the need for natural gasat the MCFC 320, except for startup and upset operations.

Referring now to FIG. 3, a SMR-CO₂ capture system including a CO₂capture system 500 and a SMR system 600 is shown according to anotherexemplary embodiment of the present disclosure. In contrast to thesystem of FIG. 2, the flue gas from the SMR system 600 is directed tothe MCFC along a flue gas supply line 635 for CO₂ capture, instead ofbeing vented. In addition, tail gas from a PSA 650 of the SMR system 600is directed along a PSA tail gas supply line 660 to be mixed directlywith an anode exhaust from the anode 522 of the MCFC 520 for capturingCO₂. In this way, the MCFC 520 can be sized to be smaller than in atypical SMR-CO₂ capture system (such as the system of FIG. 1), since thetail gas containing about 50-60% of the CO₂ normally present in the fluegas to be captured by the MCFC 520 is directed to the anode exhaust ofthe MCFC instead. Thus, this exemplary system can provide relativelyhigher CO₂ capture, as compared to the system of FIG. 2, while stillreducing overall cost, as compared to the conventional system of FIG. 1.

According to another representative embodiment, the size of the MCFC 520is configurable to offset the power consumed by the CO₂ capture system500 and the SMR system 600. In this configuration, a relatively largepercentage of the normally emitted CO₂ (e.g., about 60% to about 70%)would still be captured by the system, but the capital cost would besignificantly reduced and the need to export power to a third partywould be eliminated or reduced.

Referring now to FIG. 4, a SMR-CO₂ capture system including a CO₂capture system 700 and a SMR system 800 is shown according to anotherexemplary embodiment of the present disclosure. As shown in FIG. 4, fluegas from the SMR system 800 is directed along a flue gas supply line 835to the cathode 724 of an MCFC 720, and tail gas from a PSA 850 of theSMR system 800 is directed along a PSA tail gas supply line 860 to bemixed directly with an anode exhaust from the anode 722 of the MCFC 720for capturing CO₂. The unused fuel from the anode 722 containinghydrogen and carbon monoxide (e.g., about 30%) with small amounts ofmethane, can be directed from the CO₂ capture tail gas to the PSA 850along a CO₂ capture tail gas supply line 744 to increase the hydrogenproduction of the system. In some embodiments, the CO₂ capture tail gascould be sent to a separate PSA from the PSA 850 if, for example, thePSA 850 did not have the required capacity for the additional feed. Inthis manner, this exemplary system can provide for relatively high CO₂capture and increased hydrogen production, while reducing overall cost.

Referring now to FIG. 5, a SMR-CO₂ capture system including a CO₂capture system 900 and a SMR system 1000 is shown according to anotherexemplary embodiment of the present disclosure. As shown in FIG. 5,power is received from an external source instead of using an MCFC topower the CO₂ capture system 900. The external power source could be anexisting power plant, utility grid, and/or renewable power such as solaror wind power, according to various exemplary embodiments. The tail gasfrom a PSA 1050 of the SMR system 1000 is compressed by the compressor930 and cooled by the chiller 935, such that the liquefied CO₂ can beseparated from the gas for capturing CO₂. The CO₂ capture tail gas maybe directed along a PSA tail gas supply line 942 to the PSA 1050 and/orto the reformer 1030 of the SMR system 1000, so as to increase thehydrogen production of the system and helping to prevent build-up ofinert gases in the SMR system 1000. In this manner, this exemplarysystem can provide a lower cost option for capturing CO₂, as compared toother CO₂ capture systems. It should be appreciated, however, that theamount of potential CO₂ that is released by the external power sourceshould be taken into account when estimating the amount of CO₂ reductionwith this configuration.

Referring to FIG. 6, a method of implementing the systems describedabove is shown according to an exemplary embodiment. The exemplarymethod includes a mixing step 1101 in which tail gas from the PSA of theSMR system is mixed with anode exhaust gas from the anode of the MCFC; acompression step 1103 in which the mixed gasses are compressed by acompressor; a cooling step 1105 in which the gases are cooled by, forexample, a chiller such that most of the CO₂ is output as a liquid; aseparation step 1107 in which the liquid CO₂ is separated from theresidual gases by a CO₂ separator; a collection step 1109 in which theliquid CO₂ is collected to be sequestered or used for other purposes;and a recycling step 1111, in which the residual gases are recycled foruse in one of more of an anode gas oxidizer, the anode of the MCFC, theSMR as a fuel source for the reformer, and the PSA to produce hydrogengas. In certain embodiments, the mixing step 1101 is omitted and SMRtail gas is processed without mixing with anode exhaust gas,particularly when an external power source is used in place of a MCFC.

According to a representative embodiment, tail gas from a PSA in a SMRsystem is mixed directly with an anode exhaust gas from the anode of anMCFC, where the mixture can be compressed and its temperature lowered bya chiller, such that liquefied CO₂ can be separated from the mixture tobe captured. The CO₂ from the combustor of the reformer of the SMRsystem, i.e. the flue gas from the SMR system, is not directed to theMCFC for CO₂ capture, as compared to some conventional SMR-CO₂ capturesystems. In this way, the size of the MCFC is independent of the fluegas from the SMR reformer, and instead is governed by the CO₂ capturefrom the PSA tail gas, thereby reducing the overall cost of the systemwhile still providing CO₂ capture.

According to another representative embodiment, flue gas from a SMRsystem is sent to the cathode of an MCFC, and tail gas from a PSA of theSMR system is mixed directly with an anode exhaust from the anode of theMCFC for capturing CO₂. In this way, the MCFC can be sized to be smallerthan in a typical SMR-CO₂ capture system, since the tail gas containingabout 50-60% of the CO₂ normally present in the flue gas to be capturedby the MCFC is directed to the anode exhaust of the MCFC instead. Thus,this exemplary system can provide relatively high CO₂ capture whilereducing overall cost of the system.

According to another representative embodiment, flue gas from a SMRsystem is sent to the cathode of an MCFC, and tail gas from a PSA of theSMR system is mixed directly with an anode exhaust from the anode of theMCFC for capturing CO₂. A portion of the unused fuel from the anode ofthe MCFC, following removal of CO₂ and containing hydrogen and carbonmonoxide (CO) can be directed from the CO₂ capture tail gas to the PSAto increase the hydrogen production of the system. In this manner, thisexemplary system can provide for relatively high CO₂ capture andincreased hydrogen production, while reducing overall cost of thesystem.

According to another representative embodiment, the tail gas from a PSAof the SMR system is compressed and its temperature lowered by a chillerusing an external power source (and, in cases where an absorptionchiller is used, an external heat source), such that the liquefied CO₂can be separated from the gas for capturing CO₂. The unused fuel fromthe CO₂ capture tail gas containing hydrogen, CO, residual CO₂, andother non-condensable gases may be directed to the PSA so as to increasethe hydrogen production of the system, and/or to the reformer of the SMRsystem, helping to prevent build-up of inert gases in the SMR system. Inthis manner, this exemplary system can provide a lower cost option forcapturing CO₂, as compared to some conventional SMR-CO₂ capture systems.

Disclosed herein are various embodiments of an enhanced SMR-CO₂ capturesystem capable of capturing CO₂ in a more efficient and cost effectivemanner, as compared to some conventional CO₂ capture systems using MCFC.The various embodiments disclosed herein may be capable of increasingthe amount of CO₂ captured, improving efficiency of capturing CO₂,increasing the amount of hydrogen produced, and/or reducing costsassociated with capturing CO₂.

As utilized herein, the terms “approximately,” “about,” “substantially”,and similar terms are intended to have a broad meaning in harmony withthe common and accepted usage by those of ordinary skill in the art towhich the subject matter of this disclosure pertains. It should beunderstood by those of skill in the art who review this disclosure thatthese terms are intended to allow a description of certain featuresdescribed and claimed without restricting the scope of these features tothe precise numerical ranges provided. Accordingly, these terms shouldbe interpreted as indicating that insubstantial or inconsequentialmodifications or alterations of the subject matter described and claimedare considered to be within the scope of the invention as recited in theappended claims.

The terms “coupled,” “connected,” and the like as used herein mean thejoining of two members directly or indirectly to one another. Suchjoining may be stationary (e.g., permanent) or moveable (e.g., removableor releasable). Such joining may be achieved with the two members or thetwo members and any additional intermediate members being integrallyformed as a single unitary body with one another or with the two membersor the two members and any additional intermediate members beingattached to one another.

References herein to the positions of elements (e.g., “top,” “bottom,”“above,” “below,” etc.) are merely used to describe the orientation ofvarious elements in the Figures. It should be noted that the orientationof various elements may differ according to other exemplary embodiments,and that such variations are intended to be encompassed by the presentdisclosure.

It is important to note that the construction and arrangement of thevarious exemplary embodiments are illustrative only. Although only a fewembodiments have been described in detail in this disclosure, thoseskilled in the art who review this disclosure will readily appreciatethat many modifications are possible (e.g., variations in sizes,dimensions, structures, shapes and proportions of the various elements,values of parameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter described herein. Forexample, elements shown as integrally formed may be constructed ofmultiple parts or elements, the position of elements may be reversed orotherwise varied, and the nature or number of discrete elements orpositions may be altered or varied. The order or sequence of any processor method steps may be varied or re-sequenced according to alternativeembodiments. Other substitutions, modifications, changes and omissionsmay also be made in the design, operating conditions and arrangement ofthe various exemplary embodiments without departing from the scope ofthe present invention. For example, the heat recovery heat exchangersmay be further optimized.

What is claimed is:
 1. A system for capturing carbon dioxide from asteam methane reformer system, the system for capturing carbon dioxidecomprising: a molten carbonate fuel cell comprising an anode and acathode; a compressor configured to compress a gas mixture, the gasmixture comprising exhaust gas from the anode and tail gas from thesteam methane reformer system; a chiller configured to cool the gasmixture; and a carbon dioxide separator configured to separate the gasmixture into liquefied carbon dioxide and a residual gas mixture.
 2. Thesystem of claim 1, further comprising: an anode gas oxidizer; wherein afirst portion of the residual gas mixture is directed from the carbondioxide separator to the anode of the molten carbonate fuel cell and asecond portion of the residual gas mixture is directed to the anode gasoxidizer.
 3. The system of claim 2, wherein a third portion of theresidual gas mixture is directed from the carbon dioxide separator tothe steam methane reformer system to be burned as fuel.
 4. The system ofclaim 2, wherein a third portion of the residual gas mixture is directedfrom the carbon dioxide separator to a pressure swing adsorption systemin the steam methane reformer system.
 5. The system of claim 3, whereina fourth portion of the residual gas mixture is directed from the carbondioxide separator to a pressure swing adsorption system in the steammethane reformer system.
 6. The system of claim 1, wherein flue gas froma reformer in the steam methane reformer system is vented to theatmosphere.
 7. The system of claim 2, wherein flue gas from a reformerin the steam methane reformer system is directed to the anode gasoxidizer.
 8. The system of claim 7, wherein a third portion of theresidual gas mixture is directed to a second pressure swing adsorptionsystem outside the steam methane reformer system.
 9. The system of claim3, wherein the molten carbonate fuel cell is sized to power at least oneof the system for capturing carbon dioxide or the steam methane reformersystem.
 10. The system of claim 1, wherein the steam methane reformersystem comprises a pressure swing adsorption system configured toproduce the tail gas.
 11. The system of claim 4, wherein flue gas from areformer in the steam methane reformer system is directed to the anodegas oxidizer.
 12. A system for capturing carbon dioxide from a steammethane reformer system, the system for capturing carbon dioxidecomprising: a compressor configured to compress tail gas from the steammethane reformer system; a chiller configured to cool the tail gas; anda carbon dioxide separator configured to separate the tail gas intoliquefied carbon dioxide and residual tail gas.
 13. The system of claim12, wherein the residual tail gas is directed to the steam methanereformer system to be burned as fuel.
 14. The system of claim 12,wherein the residual tail gas is directed to a pressure swing adsorptionsystem in the steam methane reformer system.
 15. The system of claim 12,wherein a first portion of the residual tail gas is directed to apressure swing adsorption system in the steam methane reformer systemand a second portion of the residual tail gas is directed to the steammethane reformer system to be burned as fuel.
 16. A method of capturingcarbon dioxide from a steam methane reformer system, the methodcomprising: mixing tail gas from the steam methane reformer system withanode exhaust gas from an anode of a molten carbonate fuel cell to forma gas mixture; compressing the gas mixture; cooling the gas mixture; andseparating the gas mixture into liquid carbon dioxide and a residual gasmixture.
 17. The method of claim 16, further comprising: directing afirst portion of the residual gas mixture to an anode gas oxidizer; anddirecting a second portion of the residual gas mixture to the anode ofthe molten carbonate fuel cell.
 18. The method of claim 17, furthercomprising: directing a third portion of the residual gas mixture to thesteam methane reformer system to be burned as fuel.
 19. The method ofclaim 17, further comprising: directing a third portion of the residualgas mixture to a pressure swing adsorption system in the steam methanereformer system.
 20. The method of claim 18, further comprising:directing a fourth portion of the residual gas mixture to a pressureswing adsorption system in the steam methane reformer system.